Programmable motor for window coverings

ABSTRACT

An architectural window covering having a programmable electric motor is disclosed. The architectural window covering includes a head rail comprising at least one cavity, a shade coupled to the head rail, a bottom rail coupled to the shade, and at least two tandem stacked motors coupled to the shade via a drive rail such that the at least two motors fit within the at least one cavity of the head rail.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.13/459,556 filed on Apr. 30, 2012, now U.S. Pat. No. 8,461,784 entitled“Programmable Motor For Window Coverings”, which is a continuation ofU.S. application Ser. No. 12/177,330 filed on Jul. 22, 2008, now U.S.Pat. No. 8,193,742 and entitled “Programmable Motor For WindowCoverings”, each of which is hereby incorporated by reference into thepresent application in their entireties.

INVENTIVE FIELD

The various embodiments of the present invention relate to electricallypowered coverings for architectural openings. More specifically,apparatuses, processes, systems and methods are disclosed for providingmotorized operation for architectural window coverings.

BACKGROUND

Methods and systems for automatically controlling window coverings havebecome desirable over the past several decades. Such systems oftenutilize some type of motor to control the operation of the windowcoverings. This motor is often implemented within the top of thearchitectural window covering in a portion referred to as the “headrail”. Because the motor may be implemented within the head rail,depending upon its size, it may cause the head rail to be undesirablylarge. It may be desirable to minimize the size of the head rail for avariety of reasons. For example, if the head rail is too large it mayobstruct the view through the window.

The size of the motor often depends upon the mechanical torque and/orlifting requirements of the window covering, which in turn, may bedependent upon the size of the window that is being covered and theparticular covering being used. In general, larger windows and/orheavier window coverings may require either a large motor that iscapable of providing an adequate amount of torque or a smaller motoralong with accompanying gearing to provide an adequate amount of torque.Both the larger motor and the smaller motor with accompanying gearingmay undesirably consume a great deal of space within the head rail ormay generate excessive noise. Thus methods and systems are needed forimplementing and controlling motors in window coverings while minimizingtheir impact on the size of the head rail.

SUMMARY

An architectural window covering having a programmable electric motor isdisclosed. The architectural window covering includes a head railcomprising at least one cavity, a shade coupled to the head rail, abottom rail coupled to the shade, and at least two tandem stacked motorscoupled to the shade via a drive rail such that the at least two motorsfit within the at least one cavity of the head rail.

A method of operating an architectural window covering is alsodisclosed. The method may comprise the operations of monitoring two ormore motors, whereby the motors are physically coupled together intandem within a head rail of the architectural window covering andwhereby the motors are electrically coupled together in a parallelfashion. The method further may comprise measuring a movementcharacteristic associated with at least one of the two or more motorsand generating an error signal based on the movement characteristicassociated with at least one of the two or more motors.

DESCRIPTION OF THE FIGURES

FIG. 1A is a perspective view of an exemplary window covering.

FIG. 1B is an end view of the exemplary architectural window coveringshown in FIG. 1A.

FIG. 2A is a top view of the exemplary architectural window coveringshown in FIGS. 1A and 1B.

FIG. 2B is an alternative tubular motor enclosure.

FIG. 2C is an exemplary drive rail encoder pattern.

FIG. 2D is an enlarged exploded partial cross-section view of thetubular motor enclosure of FIG. 2B;

FIG. 3A is an exemplary block diagram of a window covering.

FIG. 3B depicts exemplary signals associated with angular measurementsof a drive rail within a window covering.

The use of the same reference numerals in different drawings indicatessimilar or identical items.

DETAILED DESCRIPTION

A programmable motor arrangement that fits within a head rail of anarchitectural window covering is disclosed. The programmable motorarrangement may include at least two motors that are tandem stackedwithin the head rail along with accompanying circuitry. By stacking themotors in a tandem fashion, the amount of radial space that they consumewithin the head rail may be minimized. Additionally, the motors may beelectrically connected in parallel and controlled usingpulse-width-modulated signals.

The programmable motor arrangement also may include one or moredepressible switches that may be implemented in the head rail of thewindow covering. In some embodiments, these switches may be locatedproximate to LEDs that also are within the head rail and are visible tothe user through light pipes. The light pipes may be coupled physicallyto the switches and optically to the LEDs. In this manner, thecombination of the switches, LEDs, and light pipes may operate jointlyto allow the user to enter programming information into the circuitryaccompanying the motor arrangement. The LEDs may also be used tocommunicate failure of the embodiment and/or motor to the user, as wellas other statistical, historical or operational information.

FIGS. 1A and 1B show an exemplary architectural window covering assembly100 according to at least one embodiment. The assembly 100 includes ahead rail 102, a bottom rail 104, and a shade 106. (The terms “shade”and “covering” are used generally interchangeably herein.) In someembodiments, the head rail 102 and bottom rail 104 may be formed fromaluminum, plastic, or some other light weight materials. The exemplaryshade 106 shown in FIG. 1 includes an expandable and contractiblecovering made from a light fabric and/or paper, although variouscovering implementations are possible. The exemplary shade 106 also isshown to be a cellular honeycomb shade, however, a pleated shade,horizontal slats, and/or other liftable coverings may also be used.

As seen in FIGS. 1A and 1B, the head rail 102 may include a bottom panel108, a back panel 110, end caps 112 and a front panel 114. The frontpanel 114 may be hinged by pins (not shown), attached at its upper endcorners, to the end caps 112. This may facilitate access to the cavity116 within the head rail 102 behind the front panel's front surface 118.Alternatively, the front panel 114 may be hinged to the bottom member108, or even be fully removable and snapped onto the rest of the headrail 102.

FIG. 1B shows one embodiment where a plurality of lift cords 120 maydescend from within the head rail 102, pass through the cells of thehoneycomb shade 106, to the bottom rail 104 where they are secured. Assuch, the weight of the bottom rail 104 and the shade 106 may besupported by the lift cords 120. It should be noted that while the liftcords 120 are discussed herein as tubular strings, this is merely anexemplary implementation. The lift cords 120 may be made of any type ofmaterial and take many physical forms, such as ribbon shaped pieces offabric or the like. In some embodiments, the lift cords 120 may beeliminated altogether and the shade 106 may be rolled upon a shaftwithin the head rail 102.

FIG. 2A shows a top view of the cavity 116 of the head rail 102according to one embodiment. As shown, the cavity 116 may include powercircuitry 202 and two or more motors 205A-B that fit within thedimensions of the head rail 102. In some embodiments, the motors 205A-Bmay be tubular motors arranged in a tandem fashion within the head rail102. As shown, the motor 205B may physically couple to the motor 205Avia a coupler 210B. Similarly, the motor 205A may physically couple to adrive rail 212 via an output shaft 210A. In some embodiments, the driverail 212 may operatively engage a rotatable mounted reel 225, and thelift cords 120 may be positioned on the reel 225 such that they arewound and unwound about the reel 225 during operation.

In other embodiments, the motors 205A-B may be tubular motors locatedwithin a motor housing 206 as shown in FIG. 2B. The motor housing 206,in turn, may be seated within an idler ring 284. A shroud (not shown)may rest atop the idler ring 284 and be connected to a drive gear 285.As the motors 205A, 205B rotate, the motor housing 206 may remainstationary, as may the shroud. By contrast, the drive gear 285 may berotated by the action of the motors. The drive gear is connected oraffixed to the shade 106. Thus, as the drive gear rotates, the shade 106is extended or retracted depending on the direction of rotation of thegear. It should be noted that FIGS. 2A and 2B depict alternativeembodiments of a dual-motor drive system as described herein. Further,it should be noted that the layout, configuration, spacing and/or orderof elements in such embodiments may vary.

During operation, the motors 205A-B may be electrically coupled togetherin a parallel fashion. In some embodiments, the motors 205A-B may becontrolled using a pulse-width-modulated (PWM) signal. By varying theduty cycle of the PWM signal the average voltage delivered to the motors205A-B may be controlled to match the operating conditions of thearchitectural window covering 100. For example, a low average voltagefor the PWM signal (e.g., duty cycle 20%) may correspond to moving thearchitectural window covering 100 relatively slow while a high averagevoltage for the PWM signal (e.g., duty cycle 80%) may correspond tomoving the window covering relatively fast.

By implementing two or more tandem stacked motors, the head rail 102 maybe kept as compact as possible while providing additional torque tooptimize the mechanical strength provided to operate the architecturalwindow covering assembly 100. For example, if the architectural windowcovering assembly 100 is fashioned about an unusually long window, wherethe weight of the architectural window covering may be greater thannormal, one or more additional tandem stacked motors may be added to thehead rail 102 as necessary to handle the additional mechanical strengthrequirements.

In addition, the use of multiple tandem motors may allow certainembodiments to generate sufficient torque to raise or lower the shade106 (or other covering for an architectural opening) whilesimultaneously reducing gearbox ratios. In a standard drive system for ashade, a single motor requires a relatively high rotational speed giventhe gearing of the motor. This, in turn, often leads to the motorproducing an audible noise during operation. By contrast, certainembodiments may operate the motors 205A, 205B at a lower speed since thedual-motor arrangement may generate torque equivalent to a single-motorsystem but at a lower operational speed. Accordingly, the operationalnoise of the present embodiment may be reduced and, in some cases,relatively inaudible (depending on placement of the embodiment anddistance to a listener).

As illustrated in FIG. 2A, a drive rail encoder 230 may be coupled tothe drive rail 212. The encoder 230 may include multiple regions 235angularly positioned about the drive rail 212. As the drive rail 212moves in an angular direction, the regions 235 pass by one or moreangular sensors 240 that may be read by a control circuit 245. (Thecontrol circuit is described in more detail below with regard to FIG.3A). During operation, the encoder 230 may indicate angular movement ofthe drive rail 212, such as the angular position, velocity, and/oracceleration of the drive rail 212 to name but a few. In someembodiments, the microprocessor 305 may use the encoder 230 to profilethe movement of the motors 205A-B. For example, the microprocessor 305may monitor movement of the motors to track the position of thearchitectural window covering 100 in the window.

FIG. 2B illustrates an alternative encoder arrangement where a magnet246 is coupled to the end of the motor 205A. As the motor 205A rotates,the magnet 246 may be read by a Hall Effect sensor 247 to encode thepattern of rotation or mark relative position. Position, in thisinstance, is marked relative to an index since the Hall Effect sensorcounts the number of times a pole of the magnet 246 passes the sensor.Accordingly, since the Hall Effect sensor only counts these “ticks”without reference to an absolute start, the measurement is made relativeto an index. Further, the magnet 246 typically is not a single magnet,but instead a number of magnets arrayed with opposing polesside-by-side. For example, a circular magnetic array 246 may be made ofeight (or more, or fewer) wedge-shaped magnets positioned such that thepolarity of each magnet alternates. It should be noted that the magnet246 and Hall Effect sensor 247 cooperate to replace the optical wheel230 and sensors 240 described in the embodiment shown in FIG. 2A.

FIG. 2C illustrates an exemplary drive rail encoder 235 patternarrangement including shaded 250 and unshaded 255 regions. In theembodiments where the encoder is the magnet 246, the shaded and unshadedregions 250 and 255 may correspond to regions of opposite magneticpolarity. Thus, the Hall Effect sensor 247 may profile the rotationalmovement of the magnet 246 by measuring changes in magnetic polarity. Inother embodiments, the shaded regions 250 may be physical openings inthe surface of the drive rail encoder 235 and the unshaded regions 255may be closed portions of the same. In this manner, the one or moresensors 240 may be optical sensors that detect whether light emanatesthrough the regions (as may be the case for the region 250) or light isblocked by the regions (as may be the case with the region 255).Regardless of the particular implementation, the shaded and unshadedregions 250, 255 may represent a three bit binary encoder with threeconcentric rings 260, 265, and 270. The first ring 260 may be designatedas the least significant bit, the second ring 265 may be designated asthe next most significant bit, and the third ring 270 may be designatedas the most significant bit.

In the exemplary drive rail encoder 230, the regions 250, 255collectively provide a standard binary count as the disc rotates wherethe shaded regions 255 produce a binary 1 value and the unshaded regionsprovide a binary 0 value. Groups of concentric regions may be designatedas sectors. For example, the sector between 0 and 45 degrees is shown assector 275 where all three regions within the sector 275 are unshadedand therefore the value of sector 275 is binary 000. The angularposition, velocity, and acceleration of the drive rail 212 may bedetermined by monitoring the sequence of measurements from the driverail encoder 230. For example, if the encoder readings go from 000 to111 then the drive rail 212 is moving angularly in the counter-clockwise direction. The following table summarizes the binary encoding ofthe various sectors 275-289 of the exemplary drive rail encoder shown inFIG. 2C.

Representative Sector Ring 260 Ring 270 Ring 275 Angle 275 0 0 0  0° to45° 277 0 0 1 45° to 90° 279 0 1 0  90° to 135° 281 0 1 1 135° to 180°283 1 0 0 180° to 225° 285 1 0 1 225° to 270° 287 1 1 0 270° to 315° 2891 1 1 315° to 360°

Alternative arrangements to the exemplary drive rail encoder 230 arepossible, for example, in some embodiments, Gray coding may beimplemented instead of binary encoding. In other embodiments, theencoder may be integrated with other components within the assembly 100,such as the reel 225. In still other embodiments, any number of driverail encoders 230 may be implemented, for example each of the motors205A-B may have separate encoders.

Referring again to the exemplary implementations shown in FIGS. 2A and2B, the control circuitry 245 may convert angular movement reported bythe one or more sensors 240 into electrical impulses in analog ordigital form for further processing. One or more switches 291 may becoupled to the control circuitry 245. The switches 291 may be capable ofreceiving user input, for example, by acting as a depressible switchthat is electrically coupled to the control circuitry 245. The controlcircuit 245 also may couple to one or more LEDs 292 that emanate light.In some embodiments, the LEDs 292 may communicate the operational statusof the window covering 100 to the user. In other embodiments, the LEDs292 may communicate user programming settings effectuated through theone or more switches 291. (The LEDs are not shown on FIG. 2A, but areshown on FIG. 2B.)

As shown in FIG. 2A, the one or more switches 291 and the one or moreLEDs 292 may be recessed in the head rail 102 and may couple through thecavity 116 via the one or more light pipes 293. In this manner, the oneor more light pipes 293 may be made of fiber optic material that iscapable of being formed into pathways so that light from the one or moreswitches 291 may be routed from within the cavity 116 to the user. Thus,the one or more switches 291 and the one or more LEDs 292 in combinationwith the one or more light pipes 293 may communicate various operationaland/or programming options between the user and the control circuitry245. For example, the one or more light pipes 293 may couple light fromthe one or more LEDs 292 to the user viewing the front panel 114.Additionally, the one or more light pipes 293 may be physically pressedby the user, and the one or more light pipes 293 in turn, may couplethis to the to the one or more switches 291. Thus, the one or more lightpipes 293 may provide mechanical coupling of the one or more switches291 through the cavity 116 to the user. It should be noted that onelight pipe is shown in an exploded or disassembled position while theother two are shown in an operating position.

One exemplary implementation of the switches 291, the LEDs 292, and thelight pipes 293, as shown in FIG. 2B, will now be discussed. The lightpipe 293 may be a clear plastic part with a hole 294 whereby the lightpipe 293 may pivot about this hole 294 when the light pipe 294 is fixedthrough the hole 294. Further down the light pipe 293 a foot 295 mayextend off and rests on the switch 291. The light pipe 293 may protrudethrough the motor housing 206 allowing the user to depress thisprotruding end in actuating the switch 291. By depressing the light pipe293, it may rotate about the pivot point and cause the foot 295 to pushon the switch 291.

In some embodiments, the user may program predetermined thresholds usingthe one more light pipes 293. These thresholds may include how far up ordown the architectural window covering 100 may be within the window.Also, the one or more LEDs 292 may be used to echo the programmingselections and/or stored threshold values back to the user duringprogramming. In some embodiments, these thresholds may be changeddynamically by the user operating the architectural window covering 100.

FIG. 3A represents a block diagram of the window covering 100illustrating an exemplary configuration for the control circuitry 245.As shown, the control circuit 245 may include a microprocessor 305coupled to a bridge circuit 310. In some embodiments, the bridge 310 mayinclude one or more field-effect-transistors (FETs) that provide powerto the motors 205A-B. In other embodiments, the bridge 310 includesinsulated-gate-bipolar-transistors (IGBTs) that combine the advantagesof a FET with the advantages of a bipolar transistor when providingpower to the motors 205A-B. During operation, the microprocessor maymonitor angular measurements of the motors 205A-B from the combinationof the sensor 240 and the encoder 230.

Angular measurement may also be obtained from the magnet 246 and HallEffect sensor 247, insofar as the sensor 247 may detect every time acertain magnetic polarity is adjacent the sensor. Further, the sensor247 may measure the period of each such transition. Based on theseangular measurements and the periods of transition, the microprocessor305 may determine the distance traveled and velocity of the shade 106.Additionally, based upon measurements from the combination of the sensor240, the encoder 230, and the up and down thresholds of thearchitectural window covering 100 set by the user, the microprocessor305 may determine the position of the architectural window covering 100with respect to its upper and lower extension limits. The microprocessor305 may generate one or more error signals 325 based upon the differencebetween the angular measurements of the motors 205A-B or the periods oftransitions sensed by the sensor and the desired values programmed inthe microprocessor 305 (e.g., exert positional control). In this manner,the combination of the microprocessor 305, the motors 205A-B, and theencoder 230/magnet 246 may form an adaptive feedback and control loop tocontrol overall operation of the motors 205A-B using the output of thesensor 247 or sensor 240, depending on the embodiment in question.

In particular, FIG. 3B displays an exemplary operating curve 350 forcertain embodiments when raising or lowering a shade 106. The operatingcurve 350 is shown on a graph having velocity as the Y-axis and distanceas the X-axis. Here, both velocity and distance are expressed withrespect to the shade 106 (e.g., the velocity and distance traveled ofthe shade). Initially, as the motors 205A, 205B extend or raise theshade in the manner described above, the shade's velocity varies withthe distance traveled (e.g., the shade accelerates). At a firstequilibrium point 337, the velocity of the shade is held constant as theshade continues to travel. At a second equilibrium point 339, theembodiment senses via the sensor 247/240 that the shade is nearing anendpoint of its travel. Accordingly, the motors decelerate the shadesuch that its velocity returns from a constant value to zero across acertain distance. Thus, at the end point 33, the shade's travel iscomplete and its velocity is zero. The first and second equilibriumpoints 337, 339 thus define the beginning and end of the constantvelocity portion of the operating curve 350, which is the section wherethe shade's velocity is in equilibrium.

In some embodiments, the window covering's velocity between the startingpoint 331 and the ending point 333 may be non-uniform. For example, inthe exemplary operating curve 350, the architectural window covering 100may slightly accelerate or slightly decelerate during the constantvelocity segment of the curve 350 to maintain an overall constantvelocity and, for example, to correct for error or jitter in the travelof the shade.

In some embodiments, the acceleration and deceleration portions of theoperating curve 350 may be accomplished in whole, or in part, by one ofthe motors 205A-B.

Between the equilibrium points 337, 339, the motors 205A-B may operateat a predetermined velocity 335. The predetermined velocity 335 may bepreprogrammed during manufacture of the architectural window covering100, or alternatively, may be programmed by the user after installation.

It should be noted that various operating curves may be employed. Forexample, the operating curve may be exponentially increasing instead oflinearly increasing between points 331 and 337. Furthermore, in someembodiments, the architectural window covering 100 may include atensioning sensor to determine when the architectural window covering100 reaches the top or the bottom of the window opening and theoperating curve may be modified accordingly. For example, the operatingcurve may be saw tooth shaped so that the architectural window coveringmay descend at a constant velocity for a short distance and then stop todetermine the tension in the cords 120 and adjust operation accordingly.

During non-operation, the architectural window covering 100 may be in apowered off state, for example, because the desired window position hasbeen achieved and no further adjustments in position are desired by theuser. When the user desires to move the architectural window covering100 after being powered down, the control circuit 245 may power itselfup and determine the position of the architectural window covering priorto power down. Then, upon power up, the microprocessor 305 may use thislast known position of the architectural window covering to move thearchitectural window covering 100 to the user's new desired positionaccording to the operating curve 350 and/or last known position of thecovering 100. For example, the user may set the architectural windowcovering 100 to be midway between the first and second intermediatepoints, at a third intermediate point 341, and then leave thearchitectural window covering 100 in that position for an extendedperiod of time. After a predetermined period of time (which may beprogrammed by the user into the microprocessor 305) the control circuit245 may enter a low power mode or power off completely to conservepower, and while doing so, may save the position of the architecturalwindow covering 100 prior to power down. In this example, the lastposition prior to power off is the intermediate point 341. When the userlater wants to readjust the position of the architectural windowcovering 100, the control circuit 245 may power back up, determine thatthe last position of the architectural window covering 100 was the thirdintermediate point 341, and then move the architectural window coveringaccording to the operating curve starting at the third intermediatepoint 341.

Referring again to FIG. 3A, the control circuit also may include one ormore optional (as indicated by the dashed boxes) interface andprotection circuits 315A-B. The protection circuits 315A-B may filterthe microprocessor 305 and the other circuitry within the controlcircuit 245 from external electromagnetic interference (EMI) andelectrostatic discharge (ESI). In addition, the protection circuits315A-B also may filter out internal EMI/ESI from signals coming from thecontrol circuit 245 to ensure that the control circuit 245 complies withFCC requirements.

The protection and interface circuit 315A may include one or more manualuser inputs or switches to control the position of the architecturalwindow covering 100 in the window. In some embodiments, this may includesingle-pole-single-throw type switches that are located at ageographically different location than the architectural window covering100 or the control circuit 245. In other embodiments, this may include asingle-pole-double-throw type switch that is located at a geographicallydifferent location than the architectural window covering 100 or thecontrol circuit 245. The user may program the control circuit 245 usingthe protection and interface circuit 315A by actuating the switch to theup, down, and/or neutral positions.

The protection and interface circuit 315B may include a bidirectionaldata interface such as an RQ™ type interface standard from ElectronicSolutions, Inc. of Lafayette, Colo. The RQ™ type interface is a sixconductor bidirectional full-duplex data interface. Alternativeembodiments may use the unidirectional RP type data communicationprotocol that provides simplex communication. In still otherembodiments, the protection and interface circuit 3158 may include abidirectional data protocol or communication interface, such as theZ-Wave™ interface from Zensys. Implementing Z-Wave™ allows low powerconsumption, 2-way RF, mesh networking technology and battery-to-batterysupport. During operation, Z-Wave™ mesh networking technology routes2-way command signals from one Z-Wave™ device to another aroundobstacles or radio dead spots that might occur. Additional interfacetypes may include CAN, LON, and Zigbee to name but a few.

Regardless of the type of bidirectional data interface used, theinterface may allow the microprocessor 305 to be queried as to thepresent status of the architectural window covering 100. For example, insome embodiments the architectural window covering 100 is configuredwith a graphic on it so as to display a message or logo. The message orlogo may be displayed as the architectural window covering 100 rotatesits shades back and forth, which may be a function of the position ofthe drive rail 212. Thus, the interface may be used to remotely controlthe message or logo displayed on the shades of the architectural windowcovering 100 by allowing the user to query the drive rail position.

In addition, a plurality of window coverings may be linked together viaan interface and user commands may be echoed between window coveringswithin the plurality. For example, all of the window coverings on theEast side of a building may be linked together via the interface and auser standing at one end of the building and desiring to operate all thewindow coverings in unison may provide the desired command to thearchitectural window covering the user happens to be standing by andhave the desired command echoed to all window coverings on that sameinterface.

As was mentioned above, the architectural window covering 100 mayinclude the power circuitry 202. As shown in FIG. 3A, the powercircuitry 202 may provide power to the bridge 310, the protectioncircuits 315A-B, the microcontroller 305, the one or more switches 291,and or the one or more angular sensors 240. The power circuitry 202 mayreceive a 12-24 volt DC input power and provide various output voltagelevels. For example, the interface and protection circuit 315B mayoperate at 10 volts while the microcontroller 305 may operate at 5volts. The power circuitry 202 is capable of supplying power at boththese levels as well as many others. In some embodiments, the protectioncircuit 315A may receive its power via the microcontroller 305. Inalternative embodiments, the input power may range from 12 to 40 voltsDC.

The power circuitry 202 may provide a power fail detection line to themicroprocessor 305. In the event that the power circuitry 202 detectsthat the main power supplied to the power circuitry 202 has been turnedoff, then it may warn the microcontroller 305 this has occurred via thepower fail detection line shown. The power circuitry 202 also mayinclude the ability to implement an efficient power down scheme. Inorder to give the power circuitry 202 sufficient hold-up time for themicrocontroller to execute a power down sequence, the power circuitry202 may include a capacitor that stores enough charge to power themicrocontroller while it executes the power down scheme. In someembodiments, this scheme includes determining that power is going away,for example, by the microcontroller determining that the power main hasbeen shut off. As a result, the microprocessor 305 may stop the two ormore motors 205A-B, monitor the deceleration of the encoder 230, andsave the state of the encoder for use when the architectural windowcovering is powered back on.

The above discussion is meant to be illustrative of the principles andvarious embodiments of the present invention. Numerous variations andmodifications will become apparent once the above disclosure is fullyappreciated. For example, the programmable motor arrangement may findapplication in a variety of settings outside the context ofarchitectural window coverings such as in garage door openers or withretractable projection screens. The claims should be interpreted toinclude any and all such variations and modifications. In addition, theabove description has broad application, and the discussion of anyembodiment is meant only to be exemplary, and is not intended tointimate that the scope of the disclosure, including the claims, islimited to these embodiments.

We claim:
 1. An architectural window covering, comprising: a head railcomprising at least one cavity; a shade coupled to the head rail; abottom rail coupled to the shade; and at least two tandem stacked motorscoupled to the shade, wherein: the at least two motors cooperate torotate a single drive shaft and the at least two motors fit within theat least one cavity of the head rail.
 2. The architectural windowcovering of claim 1, wherein the at least two tandem stacked motors areelectrically coupled in parallel.
 3. The architectural window coveringof claim 1, wherein the at least one cavity is defined in part by afront panel having one or more light pipes.
 4. The architectural windowcovering of claim 1, wherein the at least two tandem stacked motorsoperate according to a predefined characteristic.
 5. The architecturalwindow covering of claim 4, wherein the predefined characteristic isdefined in part by a pulse width modulated signal.
 6. The architecturalwindow covering of claim 5, further comprising a microprocessor thatstores positional information of the architectural window covering priorto powering the architectural window covering off.
 7. The architecturalwindow covering of claim 6, where the architectural window coveringoperates along the predetermined characteristic at a position stored inthe microprocessor prior to powering the architectural window coveringoff.
 8. The architectural window covering of claim 1, further comprisingan encoder coupled to the shaft, wherein the movement of thearchitectural window covering is profiled using the encoder.
 9. Thearchitectural window covering of claim 8, wherein each of the at leasttwo tandem stacked motors includes an encoder.
 10. A method of operatingan architectural window covering, comprising the operations of:monitoring two or more motors that cooperate to rotate a drive shaft,whereby the motors are physically coupled together in tandem within ahead rail of the architectural window covering and whereby the motorsare electrically coupled together in a parallel fashion; measuring amovement characteristic associated with at least one of the two or moremotors; and generating an error signal based on the movementcharacteristic associated with at least one of the two or more motors.11. The method of claim 10, wherein the error signal comprises amodulated signal representing the difference between a desired movementcharacteristic and the measured movement characteristic.
 12. The methodof claim 10, further comprising the operation of programming themovement characteristic using one or more switches.
 13. The method ofclaim 12, wherein the operation of programming the movementcharacteristic includes the speed at which the architectural windowcovering moves within a window.
 14. The method of claim 12, wherein theoperation of monitoring includes utilizing a magnetic encoder.
 15. Themethod of claim 14, further comprising the operation of profilingpositional information about the two or more motors based onmeasurements from the magnetic encoder.
 16. The method of claim 13,further comprising the operation of storing positional information forthe architectural window covering prior to powering down thearchitectural window covering.